Question 6.1: Balancing a Chemical Equation Propane, C3H8, is a colorless,......

Follow the four steps described in the text:

Step 1 Write the unbalanced equation using correct chemical formulas for all substances:

Step 2 Find coefficients to balance the equation. It’s usually best to begin with the most complex substance—in this case $C_3H_8$—and to deal with one element at a time. Look at the unbalanced equation, and note that there are 3 carbon atoms on the left side of the equation but only 1 on the right side. If we add a coefficient of 3 to $CO_2$ on the right, the carbons balance:

Next, look at the number of hydrogen atoms. There are 8 hydrogens on the left but only 2 (in $H_2O$) on the right. By adding a coefficient of 4 to the $H_2O$ on the right, the hydrogens balance:

Finally, look at the number of oxygen atoms. There are 2 on the left but 10 on the right. By adding a coefficient of 5 to the $O_2$ on the left, the oxygens balance:

Step 3 Make sure the coefficients are reduced to their smallest whole-number values. In this case, our answer is already correct, but we might have arrived at a different answer through trial and error:

Although the preceding equation is balanced, the coefficients are not the smallest whole numbers. It would be necessary to divide all coefficients by 2 to reach the final equation.

Step 4 Check your answer. Count the numbers and kinds of atoms on both sides of the equation to make sure they’re the same: